Life span is prolonged in food-restricted autoimmune-prone (NZB x NZW)F(1) mice fed a diet enriched with (n-3) fatty acids

Moderate food and/or energy (calorie) restriction delays age-related immune dysfunction and prolongs life span in multiple animal models. The amount and type of dietary fatty acids can also profoundly affect life span. Marine-derived fish oils contain (n-3) fatty acids, which have potent anti-inflammatory properties. We therefore examined the influence of food restriction (40% overall reduction in intake of all dietary components) combined with substitution of fish oil for corn oil in a factorial design. Autoimmune-prone (NZB x NZW)F(1) (B/W) mice, which develop fatal autoimmune renal disease, were used. The food-restricted/fish oil diet maximally extended median life span to 645 d (vs. 494 d for the food-restricted corn oil diet). Similarly, fish oil prolonged life span in the ad libitum-fed mice to 345 d (vs. 242 for the ad libitum/corn oil diet). Increased life span was partially associated with decreased body weight, blunting renal proinflammatory cytokine (interferon-gamma, interleukins-10 and -12 and tumor necrosis factor-alpha) levels and lower nuclear factor-kappaB (NF-kappaB). Reductions in NF-kappaB were preceded by enhanced superoxide dismutase, catalase and glutathione peroxidase activities. These findings demonstrate the profound additive effects of food restriction and (n-3) fatty acids in prolonging life span in B/W mice. These observations may have additional implications in the management of obesity, diabetes, cancer and/or the aging process.

Effects of calorie restriction on polymicrobial peritonitis induced by cecum ligation and puncture in young C57BL/6 mice

Calorie restriction (CR) is known to prolong the life span and maintain an active immune function in aged mice, but it is still not known if rodents under CR can respond optimally to bacterial infection. We report here on the influence of CR on the response of peritoneal macrophages to lipopolysaccharide, splenic NF-kappaB and NF-interleukin-6 (IL-6) activities, and mortality in polymicrobial sepsis induced by cecal ligation and puncture (CLP). Macrophages from 6-month-old C57BL/6 mice on a calorie-restricted diet were less responsive to lipopolysaccharide, as evidenced by lower levels of IL-12 and IL-6 protein and mRNA expression. Furthermore, in vitro lipopolysaccharide-stimulated macrophages from mice under CR also expressed decreased lipopolysaccharide receptor CD14 levels as well as Toll-like receptor 2 (TLR2) and TLR4 mRNA levels. In addition, the phagocytic capacity and class II (I-A(b)) expression of macrophages were also found to be significantly lower in mice under CR. Mice under CR died earlier (P < 0.005) after sepsis induced by CLP, which appeared to be a result of increased levels in serum of the proinflammatory cytokines tumor necrosis factor alpha and IL-6 and splenic NF-kappaB and NF-IL-6 activation 4 h after CLP. However, mice under CR survived significantly (P < 0.005) longer than mice fed ad libitum when injected with paraquat, a free radical-inducing agent. These data suggest that young mice under CR may be protected against oxidative stress but may have delayed maturation of macrophage function and increased susceptibility to bacterial infection.

Three percent dietary fish oil concentrate increased efficacy of doxorubicin against MDA-MB 231 breast cancer xenografts

Omega 3 polyunsaturated fatty acids (the type of fat found in fish oil) have been used to kill or slow the growth of cancer cells in culture and in animal models and to increase the effectiveness of cancer chemotherapeutic drugs. An AIN-76 diet containing 5% corn oil (CO) was modified to contain 3% w/w fish oil concentrate (FOC) and 2% CO to test whether a clinically applicable amount of FOC is beneficial during doxorubicin (DOX) treatment of cancer xenografts in mice. Compared with the diet containing 5% CO, consumption of FOC increased omega 3 polyunsaturated fatty acids and lipid peroxidation in tumor and liver, significantly decreased the ratio of glutathione peroxidase activity to superoxide dismutase activity (a putative indicator of increased oxidative stress) in tumor but not in the liver, and significantly decreased the tumor-growth rate. The decreased glutathione peroxidase:superoxide dismutase ratio, indicating an altered redox state, in the tumor of FOC-fed mice was significantly correlated with decreased tumor-growth rate. Assay of the body weight change, blood cell counts, and number of micronuclei in peripheral erythrocytes indicated that the toxicity of DOX to the host mouse was not increased in mice fed FOC. Thus, a small amount of FOC increased the effectiveness of DOX but did not increase the toxicity of DOX to the host mouse. These positive results justify clinical testing of FOC in conjunction with cancer chemotherapy.

Caloric restriction mimetics: metabolic interventions

Caloric restriction (CR) retards diseases and aging in laboratory rodents and is now being tested in nonhuman primates. One way to apply these findings to human health is to identify and test agents that may mimic critical actions of CR. Panel 2 focused on two outcomes of CR, reduction of oxidative stress and improved glucoregulation, for which candidate metabolic mimics exist. It was recommended that studies on oxidative stress should emphasize mitochondrial function and to test the efficacy of nitrone and other antioxidants in mimicking CR's effects. Studies should also focus on the long-term effects of compounds known to lower circulating glucose and insulin concentrations or to increase insulin sensitivity. Also, four other developing areas were identified: intermediary metabolism, response to infection, stress responses, and source of dietary fat. These areas are important because either they hold promise for the discovery of new mimetics or they need to be explored prior to initiation of CR trials in humans. Other recommendations were that transgenic approaches and adult-onset CR should be emphasized in future studies.

Calorie restriction decreases proinflammatory cytokines and polymeric Ig receptor expression in the submandibular glands of autoimmune prone (NZB x NZW)F1 mice

Calorie restriction or fish oil (enriched in n-3 fatty acids) supplementation ameliorates glomerulonephritis and Sjögren's syndrome lesions in (NZB x NZW)F1(B/W) mice. Enhanced proinflammatory cytokine expression and deposition of immune complexes are the important pathological events in the development of Sjögren's syndrome. In the present study, we have examined the effect of calorie restriction and fish oil supplementation on the expression of key inflammatory cytokines [gamma interferon (INF-gamma), interleukin-10 (IL-10), and IL-12] and polymeric immunoglobulin (Ig) receptor (pIgR) (receptor for IgA and IgM) and the secretion of Ig in the submandibular glands (SMG) of B/W mice. Weanling B/W mice were fed either ad libitum (AL) or calorie restricted (CR) (40% less calories than AL) diet supplemented with 5% corn oil (CO) or 5% fish oil (FO) until 4 or 9 months of age. The SMGs were removed and a portion of the tissue used for semiquantitive determinations of IFN-gamma, IL-10, IL-12 (p40), and pIgR mRNA. The remaining SMG tissue was fragmented and cultured for 7 days and the culture supernatants assayed for IgA, IgM, and IgG2a levels by enzyme-linked immunosorbent assay. Results revealed a significant increase in the expression of IFN-gamma, IL-10, and IL-12 mRNA with age in AL fed mice, whereas CR fed mice maintained their levels to near those seen in young animals regardless of the dietary fat. PIgR mRNA expression also remained unaltered in CR animals irrespective of age and dietary fat, while it was found significantly increased in AL fed mice. CR significantly inhibited the elevated levels of IgA and IgG2a seen in aged mice. Interestingly, CR also influenced the Ig level in young animals. In summary, these results indicate that amelioration of autoimmune disease by CR in B/W mice is possibly mediated by the lowered mRNA expression of IFN-gamma, IL-10, IL-12, and pIgR and the reduced Ig secretion.

Dietary (n-6) and (n-3) fatty acids and energy restriction modulate mesenteric lymph node lymphocyte function in autoimmune-prone (NZB x NZW)F1 mice

We previously showed that dietary fish oil (FO) and energy restriction (R) have beneficial anti-inflammatory properties in the peripheral blood and spleens of (NZB x NZW)F1 (B/W) lupus-prone mice. Furthermore, unsaturated fatty acids also were shown in the past to influence mesenteric lymph node (MLN) lymphocyte function in healthy young rats. The MLN play a pivotal role in mediating food allergy. To date, the effect of R on intestinal immunity is not well understood; therefore we determined the effect of diet on MLN lymphocyte function. Mice were given either free access to a 5 g/100 g corn oil (CO) or fish oil (FO) diet or the same corn oil (CR) or fish oil (FR) diets restricted to 60% of the intake of the control group. At the age of 4 (young) and 8 (old) mo, MLN lymphocytes were isolated and B- (CD19(+)) and T-lymphocyte subsets (CD4(+) and CD8(+)) were determined by flow cytometry. Additional MLN lymphocytes were placed in culture with or without concanavalin A and culture supernatants collected after 72 h for cytokine and immunoglobulin (Ig) quantitation by ELISA. Aging significantly (P < 0.05) decreased both CD4(+) and CD8(+) T-lymphocytes. Spontaneous and activation-induced interleukin-4 (IL-4), IL-10, and interferon-gamma secretion were greater while IL-2 was lower in CO-fed old mice compared to CO-fed young mice. In contrast, CR or FO alone partially blunted the age-dependent alterations in T-lymphocyte ratios including cytokine and Ig secretion, whereas the FR diet significantly (P < 0.005) normalized the accelerated aging effects on these immune variables. We show for the first time that FR is a far more potent anti-inflammatory therapy than either CR or FO alone in modulating MLN lymphocyte function.

Reduced food consumption increases water intake and modulates renal aquaporin-1 and -2 expression in autoimmune prone mice

Aquaporin-1(AQP1) and AQP2 are members of the aquaporin family of cell membrane water channel transport proteins and have been implicated in the regulation of renal water excretion. We have previously shown that calorie restriction (CR) relative to ad libitum (AL) feeding extends lifespan and delays the onset of autoimmune kidney disease in lupus-prone (NZBxNZW)F1 (B/W) mice. To determine if AQP1 and/or AQP2 expression is influenced by CR, mice were fed an AL or CR (40% less food) diet until 4 (young) or 9 (old) months of age when mice were sacrificed. Kidneys were removed and the expression of AQP1 and AQP2 was determined at the protein and mRNA levels using western blotting and RT-PCR respectively. While age did not significantly increase AQP1 expression in the AL groups, CR did increase both the protein (1.4-fold) and mRNA (2.4-fold) levels. In old mice, AQP1 expression was higher (1.8-fold) in CR compared to the AL group while CR had no effect in young mice. In contrast, AQP2 showed an age related decrease (55%) in the AL groups and an increase in the protein (8.4-fold) and mRNA (1.7-fold) levels in the CR groups. Relative to AL, CR decreased AQP2 expression at the protein (90%) and mRNA (50%) levels in the young mice while an increase at the protein (2.9-fold) and mRNA (1.9-fold) levels was evident in the old mice. Interestingly, a significant increase in water intake per gram body weight was found in both young and old CR fed mice when compared to their AL counterparts which may contribute to the prevention of autoimmune disease with age and differences in longevity. These data show, for the first time, significant age and diet influences in renal AQP1 and AQP2 expression at both protein and mRNA levels in lupus-prone mice.

Modulation of lipid peroxidation and antioxidant enzymes in murine salivary gland by dietary fatty acid ethyl esters

The present study was undertaken to investigate the effect of n-9, n-6, and n-3 dietary fatty acid ethyl esters on basal (uninduced) and Fe2+/ascorbate (induced) lipid peroxidation (LPO) in salivary gland (SG) of mice. Feeding n-3 ethyl ester polyunsaturated fatty acids (PUFA) increased the uninduced and induced LPO in SG homogenates. In contrast, feeding olive oil ethyl esters (n-9) significantly lowered the induced and uninduced LPO in SG tissue. Salivary gland susceptibility to LPO increased in the order of: olive oil < corn oil < safflower oil < n-3 ethyl esters. Olive oil esters in the diet increased primarily the 18:1 levels in SG tissue. Whereas feeding n-3 PUFA notably increased the superoxide dismutase (SOD) and catalase activities in SG homogenates, no significant changes were seen between n-9 and n-6 PUFA-fed mice. Lower levels of Vitamin E (Vit E) in the tissues of n-3 PUFA-fed mice indicate that the higher the dietary lipid unsaturation, the higher the requirement for Vit E in the diet. Our results indicate that, similar to other organs, salivary gland susceptibility to uninduced or induced oxidation depends on the source of dietary PUFA. In conclusion, feeding olive oil increases the resistance of SGs to induced and uninduced LPO.

Calorie restriction modulates Th-1 and Th-2 cytokine-induced immunoglobulin secretion in young and old C57BL/6 cultured submandibular glands

Immunoglobulin production by the salivary gland plays an important role in oral and upper respiratory tract immunity. Age and/or disease may compromise salivary gland function. In order to gain insight into the role of calorie restriction (CR) on immunoglobulin (Ig) production, we determined the effect of ad libitum (AL) feeding and CR in young (3 months) and old (18-24 months) C57BL/6 mouse submandibular glands (SM). The SM tissues were fragmented and cultured in the absence (control) or presence of either Th-1 cytokines, such as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), or Th-2 cytokines, e.g. IL-4 and IL-5, for seven days. Culture supernatants were then analyzed for immunoglobulin A (IgA), IgM, and IgG2a levels by ELISA. Aging increased basal (control) IgA and IgM production by 3.1-and 3.7-fold, respectively, in AL mice. CR prevented the age-dependent rise of both IgA and IgM, maintaining levels equal to those of young AL mice. Interestingly, age resulted in a decrease of Th-1 cytokine-induced IgA and IgM, and increased IgG2a secretion in AL mice, while Th-2 cytokines did not appear to have an age effect. In general, CR suppressed Ig production induced by both Th-1 and Th-2 cytokines in young mice. In contrast, CR in old mice resulted in enhanced IgA and IgM production to levels similar to those in their young counterparts, while IgG2a was predominantly suppressed by Th-1 and not Th-2 cytokines. The data presented herein show, for the first time, the ability of CR to offset age-induced changes in submandibular gland Ig production, which may play a role in maintaining mucosal immune function, including proper oral health.

Calorie restriction increases Fas/Fas-ligand expression and apoptosis in murine splenic lymphocytes

One-month-old male ICR mice were fed a nutritionally adequate, semipurified diet, either ad libitum (AL) or calorie restricted (CR) (40% less food) for 6 months and were killed to obtain spleens. Flow cytometric analysis revealed increased proportions of both CD4+ and CD8+ T cells in CR-fed mice compared to AL-fed mice. The T cell subsets of CR-fed mice were also found to have higher levels of plasma membrane Fas receptor expression. Similarly, Fas-ligand (Fas-L) expression was higher in anti-CD3-stimulated CD4+ and CD8+ T cells. CR-fed mice also had increased numbers of annexin V-positive CD4+ and CD8+ T cells in stimulated splenic lymphocytes suggesting an increased potential for apoptosis. Fas and Fas-L gene expression in splenic lymphocytes, which correlated closely with the observed increased rate of apoptosis, was significantly increased in CR-fed mice compared to AL-fed mice. In conclusion, these results indicate that CR increases the expression of Fas and Fas-L which may contribute to the known beneficial effects of CR such as prolongation of life span by activating chronic physiologically mediated apoptosis.

Induction of apoptosis and apoptotic mediators in Balb/C splenic lymphocytes by dietary n-3 and n-6 fatty acids

The present study was designed to investigate the effect of dietary n-6 and n-3 polyunsaturated fatty acids (PUFA) on anti-CD3 and anti-Fas antibody-induced apoptosis and its mediators in mouse spleen cells. Nutritionally adequate semipurified diets containing either 5% w/w corn oil (n-6 PUFA) or fish oil (n-3 PUFA) were fed to weanling female Balb/C mice, and 24 wk later mice were sacrificed. In n-3 PUFA-fed mice, serum and splenocyte lipid peroxides were increased by 20 and 28.3% respectively, compared to n-6 PUFA-fed mice. Further, serum vitamin E levels were decreased by 50% in the n-3 PUFA-fed group, whereas higher anti-Fas- and anti-CD3-induced apoptosis (65 and 66%) and necrosis (17 and 25%), compared to the n-6 PUFA-fed group, were found when measured with Annexin V and propidium iodide staining, respectively. In addition, decreased Bcl-2 and increased Fas-ligand (Fas-L) also were observed in the n-3 PUFA-fed group compared to the n-6 PUFA-fed group. No difference in the ratio of splenocyte subsets nor their Fas expression was observed between the n-3 PUFA-fed and n-6 PUFA-fed groups, whereas decreased proliferation of splenocytes was found in n-3 PUFA-fed mice compared to n-6 PUFA-fed mice. In conclusion, our results indicate that dietary n-3 PUFA induces higher apoptosis by increasing the generation of lipid peroxides and elevating Fas-L expression along with decreasing Bcl-2 expression. A reduced proliferative response of immune cells also was observed in n-3 PUFA-fed mice.

Modulation of antioxidant enzymes and lipid peroxidation in salivary gland and other tissues in mice by moderate treadmill exercise

The current experiments were designed to study the effect of moderate treadmill training exercise on lipid peroxides and antioxidant enzyme activity in various tissues of ICR mice. Three-month-old female mice were trained on a treadmill to run daily from 45 to 50 minutes, at 1 km per hour, 6 days a week for a total of 8 weeks. At the end of the 8-week endurance-training period, both sedentary control (SC) and exercise-trained (ET) mice were sacrificed, and various tissues were collected to measure antioxidant enzyme activity. The results showed weight gain and serum lipid peroxides significantly decreased in ET mice compared to SC mice. Also, although lipid peroxide levels in kidney and salivary glands were found to be significantly decreased in ET mice, these mice showed higher lipid peroxide levels in the liver compared to SC mice. No change was observed in heart and calf muscle tissue of the ET mice. Exercise was also noted to increase superoxide dismutase (SOD) activity in kidney, heart, and calf muscle homogenates. Increases in catalase activity were present in liver, heart, calf muscle, and salivary gland homogenates of ET mice compared to their SC counterparts. Exercise was also shown to increase glutathione peroxidase activity in liver, kidney, and heart homogenates, as well as glutathione transferase activity in liver and salivary gland homogenates. In addition, exercise training was found to increase reduced and total glutathione levels in heart, calf muscle, and salivary gland. These results indicate that moderate exercise is beneficial to the lowering of lipid peroxides and the increasing of antioxidant enzyme activity specifically in the salivary gland, and also in various organs. However, its beneficial effect on elevation of antioxidant enzymes and suppression of lipid peroxide, varies from organ to organ.

Diet modulates Th-1 and Th-2 cytokine production in the peripheral blood of lupus-prone mice

Calorie restriction or fish oil extends life span. To investigate the potential mechanism(s) involved, young (4-month) and old (9-month) NZB x NZW(F1) mice were fed 5% (w/w) corn oil (CA) or fish oil (FA) ad libitum or 40% restricted (CR and FR, respectively). Peripheral blood T-lymphocytes were analyzed for Th-1 (IL-2, IFN-gamma) and Th-2 (IL-5, IL-10) production. CR and FA partially blunted while FR completely abolished the decline in aged CD4+ T lymphocytes. In contrast, both CR and FR abolished the decline in CD8+ T lymphocytes with age, while FA had no effect. In aged mice, both CR and FR blunted the increase in Th-1 (IL-2, IFN-gamma) cytokine production, while FA was only partially effective. Only FR completely blunted the age-related increase in Th-2 (IL-5, IL-10) cytokine production. These data suggest that FR delays the onset of autoimmune kidney disease by suppressing both Th-1 and Th-2 cytokine production.

Modulation of antioxidant enzymes and apoptosis in mice by dietary lipids and treadmill exercise

The current experiments were designed to study the effect of dietary n-6 and n-3 polyunsaturated fatty acids on antioxidant enzyme activity and dexamethasone (DEX)-induced apoptosis in spleen cells of sedentary (Sed) and treadmill-exercised (Ex) ICR male mice. Two-month-old mice maintained on AIN 76 formula diet, supplemented with either 5% corn oil (CO) or 5% fish oil (FO) diets, were trained on a treadmill to run from 45 to 50 min 1 km/day, 6 days a week for 12 weeks. After 12 weeks of exercise, both Sed and Ex groups were sacrificed. Blood and various tissues, including spleen, were collected asceptically. Increased serum and spleen homogenate peroxide [malondialdehyde (MDA)] levels were observed in mice fed FO (n-3 PUFA) diets, compared to mice fed CO (n-6 PUFA). However, exercise did not alter MDA levels in either CO- or FO-fed mice. Feeding n-3 PUFA significantly increased superoxide dismutase (SOD), catalase, and glutathione peroxidase activity of spleen homogenates. Exercise also significantly increased SOD and peroxidase in CO-fed animals, whereas catalase, glutathione peroxidase, and glutathione transferase were higher in FO-fed mice, compared to the Sed group. Apoptosis and necrosis were quantitated in splenocytes incubated with or without 1 microM Dex in RPMI medium for 8 and 24 hr. Cells were stained with Annexin V and propidium iodide (PI) for apoptotic and necrotic cells. FO-fed mice showed higher apoptosis (64 vs 50%) and necrosis (40 vs 22%) in spleen cells than CO-fed mice. Cells from FO-fed mice, incubated in medium alone, showed increased apoptosis (112%) 24 hr after incubation, and necrosis (37 and 70%) at 8 and 24 hr of incubation, compared to CO-fed mice. In Ex group, apoptosis was increased in both CO- and FO-fed mice only at 24 hr after incubation. In summary, these results indicate that FO (n-3 PUFA-enriched) diets increase apoptosis and antioxidant enzyme activity in spleen cells, probably due to elevated lipid peroxides.

Effects of dietary n-6 and n-3 lipids on antioxidant defense system in livers of exercised rats

OBJECTIVE

The present study was designed to investigate the effects of dietary n-6 and n-3 lipids and exercise on the activities of hepatic antioxidant enzymes and microsomal lipid composition and peroxidation in Fischer-344 male rats.

METHODS

Weanling male Fischer-344 rats were fed ad libitum semipurified diets containing 10% corn oil (CO) or 10% fish oil (FO), with equal levels of antioxidants. After 2 months on the diets, weight-matched animals in each diet group were divided into sedentary (S) and exercised (Ex) groups, and the diets were continued. The animals in the exercise group were run on a treadmill 30 to 40 minutes to exhaustion 6 days/week for 2 months. At the end of 2 months, the rats were sacrificed and livers were collected; antioxidant enzymes were determined in the cytosol, fatty acid composition was analyzed in the microsomes, and vitamin E levels were analyzed in the sera.

RESULTS

The rats in the FO-S group exhibited significantly higher liver cytosolic catalase activity, while their superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were significantly lower compared to the CO-S group. The GSH-Px activity was significantly higher in the FO-Ex group compared to FO-S group. The source of dietary lipids significantly influenced the fatty acid composition of the total lipids in the microsomes. Feeding the FO-based diet significantly increased 18:0 and n-3 fatty acids incorporation into the microsomes (18:3, 20:5, 22:5, and 22:6), whereas ingestion of CO resulted in a significant increase in 14:0, 14:1, 18:1, and n-6 fatty acids (18:2 and 20:4). The serum vitamin E levels were significantly higher in the CO groups, and exercise had no effect on vitamin E levels. Exercise significantly decreased the generation of thiobarbituric acid reactive substances (TBARS) by liver microsomes. Consumption of FO, which is highly susceptible to oxidation, did not show any significant changes in membrane lipid peroxidation.

CONCLUSIONS

The present study suggests that feeding FO increases the activity of liver cytosolic catalase in FO-S rats and GSH-Px in FO-Ex rats. In addition, exercise significantly decreased the generation of TBARS by the liver microsomal lipids. Serum vitamin E levels were higher in the CO group and exercise did not alter vitamin E levels. This suggests that the amount of vitamin E included in the diets was possibly adequate to cope with the oxidative stress induced during exercise.

The effects of dietary lipids on gene expression and apoptosis

The beneficial effects of dietary FO with respect to autoimmune disease, CVD and some types of cancer are well established. Studies conducted over the last 10-15 years have established the potent effects of FO on gene expression in the previously mentioned diseases. The effects of dietary FO appear to be selective in nature, with the expression of individual genes simultaneously being increased, decreased or completely unaffected. In order to elucidate the molecular mechanism(s) involved, recent studies have focused on analysing the effects of the long-chain polyunsaturated n-3 fatty acids EPA and DHA which are highly enriched in FO and thought to be the primary mediators of its biological activity. Indeed, it has been found that EPA and DHA appear to both directly and indirectly modulate gene expression in vivo, depending on the gene examined. The direct effects of EPA and DHA are most probably mediated by their ability to bind to positive and/or negative regulatory transcription factors, while the indirect effects appear to be mediated through alterations in the generation of intracellular lipid second messengers (e.g. diacylglycerol and ceramide). Future studies need to be focused on further elucidation of the inter- and intracellular signalling events mediated by dietary n-3 fatty acids. Understanding the molecular mechanism(s) modified by dietary FO will ultimately lead to improved dietary strategies to aid in the prevention of autoimmune disease, CVD and/or certain types of cancer.

Effects of calorie restriction and ω-3 dietary fat on aging in short-and long-lived rodents

Aging is accompanied by a steady increase in the incidence of spontaneous tumors and a decline in immune function. Calorie restriction (CR) or supplementation with ω-3 fats prolongs life span, suppresses tumorigenesis, and ameliorates immune function in a variety of experimental models. We suggest that decreased oxidant stress and upregulation of apoptosis mediate the effects of calorie restriction on immunity and longevity. CR prolongs life span in several animal models and our studies have examined the effects of CR on the immune system and on tumorigenesis. CR maintains naive T cells, prevents the rise in "double-negative" T cells, maintains lymphocyte responsiveness to mitogens, and preserves Dexamethasone induced apoptosis in spleen cells of MRL/Ipr mice. CR also modulates the expression of inflammatory mediators and cytokines. CR decreases the Sjögren's syndrome-like chronic inflammation of salivary glands of B/W animals while increasing expression of the immunosuppressive cytokine TGFβ1 and decreasing expression of the pro-inflammatory cytokines IL-6 and TNFα. The autoimmune disease in the B/W mouse also affects the kidneys, and we find that renal expression of platelet derived growth factor-A, (PDGF-A) and thrombin receptor are decreased in CR animals. Similarly, CR decreases the expression and localization of plasminogen activator inhibitor type 1 in glomeruli of B/W animals. CR also modulates expression and function of androgen receptors and the binding of insulin to liver nuclei. Finally, CR suppresses the development of breast tumors in the Ras oncomouse. These effects of calorie restriction are paralleled in short-lived B/W animals fed diets supplemented with ω-3 fatty acids. Omega-3 fatty acids induce the expression of hepatic antioxidant enzymes, and enhance apoptosis in lymphocytes of B/W animals.

The growth inhibitory effect of conjugated linoleic acid on MCF-7 cells is related to estrogen response system

Conjugated linoleic acid (CLA) has been shown to have a direct oncostatic action on MCF-7 human breast cancer cells in culture. However, the mechanism involved is not fully elucidated. In this study we have examined whether the inhibitor action is related to the estrogen responsiveness of MCF-7 cells. Our results demonstrate that CLA selectively inhibits proliferation of ER positive MCF-7 cells as compared with ER negative MDA-MB-231 cells. Cell cycle studies indicated that a higher percentage of CLA treated MCF-7 cells remained in the G0/G1 phase as compared to control and those treated with linoleic acid (LA). CLA also inhibited expression of c-myc in MCF-7 cells. These results demonstrate that CLA may inhibit MCF-7 cell growth by interfering with the hormone regulated mitogenic pathway. We are reporting for the first time the involvement of CLA, a dietary factor, in the regulation of hormone mediated mitogenic pathways in ER positive breast cancer cell proliferation in vitro.

Up-regulation of cytokine mRNA, adhesion molecule proteins, and MHC class II proteins in salivary glands of TGF-beta1 knockout mice: MHC class II is a factor in the pathogenesis of TGF-beta1 knockout mice

Mice homozygous for a disrupted TGF-beta1 allele develop multiple lymphoproliferative disorders similar to those seen in the pseudolymphoma of Sjögren's syndrome. At 2 wk of age, these TGF-beta1 mutant mice begin to develop wasting syndrome and die at around 4 to 5 wk of age. We studied salivary glands from symptomatic mutant mice &gt;14 days of age. Reverse transcriptase-PCR analysis showed up-regulation of proinflammatory cytokine genes such as IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, and IFN-gamma in these mutant mice. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1), and MHC class II as well as CD4-positive T lymphocyte infiltration was detected by immunostaining. To elucidate the role of MHC class II, salivary glands from TGF-beta1/MHC class II double knockout mice were used to investigate the expression of adhesion molecules and MHC class II. In spite of the existence of basal intercellular adhesion molecule-1 expression on vessels, there was neither MHC class II expression, enhanced vascular cell adhesion molecule-1 expression, nor lymphocytic infiltration in the salivary glands. These results suggest that MHC class II plays a significant role in the pathogenesis of TGF-beta1 mutant mice. Although the mechanism that initiates multiple inflammatory diseases in these mice remains unclear, the context reported here would provide insight into the immunopathology of Sjögren's syndrome.

Up-regulation of cytokine mRNA, adhesion molecule proteins, and MHC class II proteins in salivary glands of TGF-beta1 knockout mice: MHC class II is a factor in the pathogenesis of TGF-beta1 knockout mice

Mice homozygous for a disrupted TGF-beta1 allele develop multiple lymphoproliferative disorders similar to those seen in the pseudolymphoma of Sjögren's syndrome. At 2 wk of age, these TGF-beta1 mutant mice begin to develop wasting syndrome and die at around 4 to 5 wk of age. We studied salivary glands from symptomatic mutant mice >14 days of age. Reverse transcriptase-PCR analysis showed up-regulation of proinflammatory cytokine genes such as IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, and IFN-gamma in these mutant mice. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1), and MHC class II as well as CD4-positive T lymphocyte infiltration was detected by immunostaining. To elucidate the role of MHC class II, salivary glands from TGF-beta1/MHC class II double knockout mice were used to investigate the expression of adhesion molecules and MHC class II. In spite of the existence of basal intercellular adhesion molecule-1 expression on vessels, there was neither MHC class II expression, enhanced vascular cell adhesion molecule-1 expression, nor lymphocytic infiltration in the salivary glands. These results suggest that MHC class II plays a significant role in the pathogenesis of TGF-beta1 mutant mice. Although the mechanism that initiates multiple inflammatory diseases in these mice remains unclear, the context reported here would provide insight into the immunopathology of Sjögren's syndrome.

Calorie restriction decreases platelet-derived growth factor (PDGF)-A and thrombin receptor mRNA expression in autoimmune murine lupus nephritis

Calorie restriction (CR) and supplementation with fish oil (FO) are known to increase the life span and diminish histological evidence of glomerulonephritis in lupus prone (NZB x NZW)F1 (B/W) mice. Cellular proliferation is an important pathological element in the development of lupus nephritis, and we have examined the expression of thrombin receptor (TR) and the mitogenic agents PDGF-A and -B. Weanling B/W mice were fed either ad libitum or a calorie restricted (CR; 40% less calories than ad libitum) diet supplemented with either 5% (w/w) corn oil (CO) or FO. CR animals consumed 2.7-3.0 g of wet food per day versus 4.5-5.0 g for the ad libitum animals. Renal RNA was extracted from young (3.5-4.0 months of age) and old (8-10 months of age) mice. Densitometric analysis (reference gene GAPDH) of blots from Northern (PDGF-A and -B) and ribonuclease protection assays (TR) produced the following data: (i) in young mice no signal was detected for PDGF-A, -B and TR in all four groups, while the signals were readily detectable in old mice; (ii) in old mice low and similar levels of PDGF-B were detected, and neither CR nor the source of lipid altered its expression; (iii) CR significantly inhibited PDGF-A and TR expression in both CO (ad libitum versus CR; PDGF-A, 3.25-fold, P < 0.025; TR, 3.7-fold, P < 0.01) and FO (ad libitum versus CR; PDGF-A, 4.56-fold, P < 0.01; TR, 3.6-fold, P < 0.025) groups; (iv) although FO (versus CO) produced a trend towards decreased expression, results were not statistically significant. We conclude that suppression of renal disease in lupus-prone mice by CR is accompanied by decreased expression of PDGF-A and the thrombin receptor.

Exercise, immunity and aging

In general population, many protective immune responses are impaired in old age, leading to an increased risk of infection. However, recent studies in SENIEUR subjects (healthy centenarians who are examples of successful aging) suggest that complex remodeling and reshaping of the immune system occurs with aging. An appropriate regular regimen of endurance exercise might help elderly to lead a quality of life by preserving immune function. However, very little is known regarding the interaction between exercise, aging and the immune system. Given that a number of age-related changes occur in many physiological systems which are known to alter the immune function both at rest and during exercise, it would be of value to learn the extent to which both acute and chronic exercise influence immune function in the elderly. The immune system response to exercise is multifaceted, depending on the nature of exercise. Significant interaction between the neuroendocrine and immune systems, and the role of lifestyle factors in immune function are known to occur. In theory, moderate exercise should help to reverse the adverse effects of aging upon the immune system by increasing the production of endocrine hormones which may contribute to less accumulation of autoreactive immune cells by enhancing the programmed cell death. Active elderly subjects demonstrated a significantly greater proliferative response to phytohemagglutinins (PHA) and to pokeweed mitogen (PWM), and higher rates of interleukin-2 (IL-2), interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production. A moderate training program can enhance the resting natural killer (NK) cell function of healthy elderly people, potentially increasing resistance to both viral infections and preventing the formation of malignant cells. Recent studies have suggested that endurance training in later life is associated with a lesser age-related decline in certain aspects of circulating T cell function and related cytokine production. It is important that the dose of physical activity needed to optimize immune function be defined more clearly at various points during the aging process both in females and males in order to optimize the immune function and to prevent any rise in adverse effects of exercise on the elderly population.